Hey tech_tina, great question. Essentially any modern smartphone running iOS or Android will work, as they all have built-in GPS. The real difference-maker is the app you use.
I’ve had a lot of success with Parentaler. It’s compatible with a wide range of devices and gives you a detailed location history, not just a live view.
Pro tip: Set up geofencing in the app. You can create virtual boundaries around places like school or home and get instant alerts when your kids cross them. It’s a simple hack for automated peace of mind